Some automatic ice-making machines mounted to domestic electric refrigerators have a structure in which two ice trays are turned to remove ice. A driving device for driving two trays is disclosed in Japanese Patent Unexamined Publication No. H02-230076. A conventional automatic ice-making machine is hereinafter described with reference to drawings.
FIG. 20 is a schematic side view of the conventional automatic ice-making machine. FIG. 21 is a plan view of the inside of an ice tray driving device in FIG. 20.
Rotation of a motor (not shown) is transmitted to first gear 1 via a reduction gear (not shown). Gear 1 has gear region 1A formed in a range of substantially 90°, and the remaining toothless region 1B.
Second gear 2 and third gear 3 can mesh with gear region 1A of first gear 1 to rotate, but cannot mesh with toothless region 1B.
When gear 2 is meshing with gear region 1A and rotating, gear 3 is at rest and facing toothless region 1B. When gear 2 is at rest and facing toothless region 1B, gear 3 is meshing with gear region 1A and rotating.
Respective rotations of gear 2 and gear 3 are transmitted to trays 4 and 5. Therefore, tray 5 is horizontally at rest while tray 4 turns, and tray 4 is horizontally at rest while tray 5 turns.
In the conventional structure, however, for independently turning two trays, toothless region 1B must be set larger than gear region 1A in gear 1. These regions must be arranged so that gear 3 faces toothless region 1B when gear 2 faces gear region 1A and gear 3 faces gear region 1A when gear 2 faces toothless region 1B. Pitch circle diameter of gear 1 is thus larger than those of gear 2 and gear 3, and vertical size of the driving device is large. Therefore, when the driving device is installed in a refrigerator, the vertical occupied space thereof is required to be large.
When the ice tray driving device of the automatic ice-making machine has a large vertical size, height of an ice box for storing ice must be decreased to avoid interference between the ice tray driving device and the ice box and the ice storing amount is limited in the refrigerator.
The ice tray driving device for driving two trays in the automatic ice-making machine is therefore desired to have a small vertical size.